Bibcode
Richard, Simon; Brook, Chris B.; Martel, Hugo; Kawata, Daisuke; Gibson, Brad K.; Sanchez-Blazquez, P.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 402, Issue 3, pp. 1489-1503.
Fecha de publicación:
3
2010
Número de citas
22
Número de citas referidas
20
Descripción
We used an N-body smoothed particle hydrodynamics algorithm, with a
detailed treatment of star formation, supernovae feedback and chemical
enrichment, to perform eight simulations of mergers between gas-rich
disc galaxies. We vary the mass ratio of the progenitors, their rotation
axes and their orbital parameters and analyse the kinematic, structural
and chemical properties of the remnants. Six of these simulations result
in the formation of a merger remnant with a disc morphology as a result
of the large gas fraction of the remnants. We show that stars formed
during the merger (a sudden starburst occurs in our simulation and lasts
for 0.2-0.3Gyr) and those formed after the merger have different
kinematical and chemical properties. The first ones are located in the
thick disc or the halo. They are partially supported by velocity
dispersion and have high [α/Fe] ratios even at metallicities as
high as [Fe/H] = -0.5. The former ones - the young component - are
located in a thin disc rotationally supported and have lower
[α/Fe] ratios. The difference in the rotational support of both
components results in the rotation of the thick disc lagging that of the
thin disc by as much as a factor of 2, as recently observed. We also
find counter-rotating stars in both the old and young populations. A
variety of structures are formed during the merger, i.e. most
simulations form a ring of young stars and two simulations formed a bar.
The scalelength of the thick disc is either equal to that of the thin
disc or larger by factors of up to 1.60 and in six out of the eight
simulations, the thin and thick discs both have exponential luminosity
profiles and are nearly coplanar. We find that, while the kinematic and
structural properties of the merger remnant depend strongly upon the
orbital parameters of the mergers, there is a remarkable uniformity in
the chemical properties of the mergers. This suggests that general
conclusions about the chemical signature of gas-rich mergers can be
drawn.
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